Project Summary A neural interface is needed that will allow for monitoring the diverse neural anatomy in chronic, behaving animal experiments. The state-of-the-art tools including both flexible surface arrays and stiff penetrating arrays have well-known limitations including low signal-to-noise and unstable recordings over time. The goal of this project is to develop and test a novel device concept that combines stretchable substrates with high-density needles to penetrate through the epineurium of ganglia and peripheral nerves. Nothing in this scale has been demonstrated or attempted to date. This approach has the potential to mitigate the poor fidelity of surface arrays and eliminate damage induced from larger penetrating arrays. Initial validation testing on ganglionic and nerve interfaces will yield a variety of control signals from the sympathetic, parasympathetic, and somatic motor and sensory pathways that innervate the bladder and lower urinary tract. Although bladder dysfunction is a significant healthcare problem, the underlying neural control is not well understood. This shortfall of knowledge results in only partially effective therapies, including drugs and neurostimulators. In Aim 1, microneedle array design and fabrication will yield several device iterations will be evaluated in benchtop phantom experiments to demonstrate insertion effectiveness and ease-of-use. In Aim 2, acute and short-term chronic in vivo experiments will allow us to further evaluate and improve usability, demonstrate signal fidelity, and perform histological evaluation. We expect that this technology and subsequent learning opportunities will lead to significant improvements in neuromodulation devices.